Application of Anisotropic Magnetoresistive sesnsors for detection of changes in organ activity

 This paper addresses the measurements of biomagnetic fields that occur in the vicinity of biological tissues using AMR (Anisotropic magnetoresistance) technology based magnetic sensors. Throughout the years of research new technologies have emerged in the field of sensorics. In biomedicine, the most commonly used and the most precise, but at the same time the most complex and expensive is the SQUID magnetometer (Superconducting Quantum Interference Device). In recent years, less costly versions of magnetometer technologies have been perfected in the form of microelectromechanical systems. The latter offer a vast variety of sensors, which work on the basis of different principles (AMR, GMR, GMI, Hall effect). The amount of academic efforts on this subject indicates a relative lack of research concerning the usage of AMR technology for measurement of biomagnetic fields, which caused by electrical properties of magnetically unexposed human body ranges from approximately 0.1 nT in the vicinity of human heart, and around 1 pT near human brain. On the other hand magnetically exposed human body with devices such as MRI, reflects several times higher values of magnetic field. Top resolution of commercially available anisotropic magnetoresistive sensors touches the bottom level of biomagnetic field's spectrum, therefore we have investigated possibilities for its improvements. The main goal of research presented in this paper is to determine whether realization of AMR based biomagnetometer and its usage for such measurements is really possible.